This invention relates to physiological electrical signal monitors and more particularly to a connector system used to connect electrodes to such monitors.
Monitors which detect and analyze physiological electrical signals, such as EEG, EKG and EMG signals, are being used for an increasing number of different purposes. For example, an EEG monitor which processes EEG signals in a manner described in U.S. Pat. Nos. 4,907,597; 5,010,891 and 5,320,109 issued to Chamoun, et al., is being used to determine a depth of anesthesia of a patient.
The medical personnel utilizing EEG monitors for purposes such as determining depth of anesthesia are not as sophisticated as the personnel which traditionally use EEG monitors for analyzing EEG signals. Operators monitoring depth of anaesthesia are often not doctors trained in neurology and are not as skilled and knowledgable concerning the proper placement of the electrodes which acquire the EEG signals from the brain. Such proper placement is further complicated by the fact that with different types of monitoring, signals from different portions of the brain are required. For example, two channel bipolar signal values are required for isolating the hemipheres of the brain, while two channel referential signal values would be required for referencing to a common point on the brain for monitoring the effects of anesthetics on the brain. Since the placement of the electrodes is extremely important to obtain proper readings, the electrodes must be placed in the appropriate locations and the appropriate type and number of electrodes must actually be used. Because the same monitor may be used to take several different modes of monitoring, electrodes must be placed in different locations and the number of required electrodes is different for different modes of monitoring.
In U.S. Pat. No. 5,265,607 which was issued to Moberg, a patient-monitoring electrode connection apparatus is described in which configuration cards are used in a data acquisition module. The problem with such a system is that the operator must not only use appropriate electrode cables and connect the electrodes properly but must also insert the appropriate configuration card. This raises the additional possibility of human error which may result if an inappropriate card is selected.
It is therefore a principal object of the present invention to provide a cable interface system which will enable a physiological electrical signal monitor to determine the type of electrode system being attached to the monitor.
It is another object of the present invention to allow physiological electrical signal monitor connector to make use of different types and numbers of electrode configurations.
A further object of the present invention is to provide an easy to use electrode-to-monitor cable connector system which is moisture resistant and includes an integral key structure which prevents connection of incompatible connectors.